Combustion-regulating method and mechanism



F. H. BROWN AND J. M. HOPWOOD.

COMBUSTION REGULATING METHOD AND MECHANISM.

APPLICATION FIL-Eo FEB. 12. 1920.

1,338,899. Patented May 4;1920.

2 SHEETS-SHEET I.

F. H. BROWN AND1. M. HoPwooD. CMBUSTION REGULATING METHOD AND MECHANISM.

PPLICAION FILED FEB. 12, 1920. I 1,338,899. Patented May 4, 1920.

2 SHEETS-SHEET 2.

www@

UNITED sTATEs PATENT OFFICE.

FRANCIS H. BROWN, 0F PHILADELPHIA, A ND JOHN M. HOPWOOD, OF PITTSBURGH,

BROWN ASSIGNOR TO SAID HOPWOOD.

COMBUSTION -REG-ULATIN G METHOD AND MECHANISM.

Specification of Letters Patent.

Patented May 4, 1920.

Substitute for application Serial No. 206,464, filed December 10, 1917. This application led February 12,

1920. Serial No. 358,090.

To all whom t may concern Be it known that we, FRANCIS H. BROWN and JOHN M. HoPwooD, residin respectively, at Philadelphia and Pittsburgh, in the counties of Philadelphia and Allegheny, respectively, and State of Pennsylvania, citizens .of the United States, have invented or discovered certain new and useful Improvements in Combustion Regulating Methods and Mechanism, of which improvements the following is a specification.

The invention described herein relates to certain improvements in the control of the operations involved in the combustiongof fuel for the heating of furnaces for metallurgical and other purposes such as continuous furnaces, sheet furnaces, etc. The invention has for its object the regulation of the flow of products of combustion from the lire box and furnace by and in accordance with the pressure of gases in the fire box or heating chamber or both, and the re ulation of the feed of fuel to the combustion chamber. The invention is hereinafter more fully described and claimed. l

In the accompanying drawings forming a part lof this specification, Figure 1 is a.

continuous billet our improvement a similar view of heating furnace sectional elevation of a heating furnace, having applied thereto; Fig. 2 is an ordinary plate or sheet having the rate of` feed of fuel and the `flow of air for combustion controlled by' and'in accordance'with the pressure of gases in the fire box or heating-chamber; Fig. 3 is a view similar to Fig. 2 showing an embodiment of the improvement in which'the regulation is effected by and inv accordance with pressures in one or more parts of the furnace; Fig. 4 is a plan View of the pressure controlled regulating mechanism employed when dual control-isf desired, and Fig. 5 is a sectional elevation, the plane of-se'ction be# ing indicated by the line V-V, Fig. 4.

It has been found in the operation of heating yfurnaces that under normal conditions the supply of air and fuel should bear a certain predetermined relation to each and uniform combustion e for the desired example, if through inattenfects. As for tion or for other reasons, the bed of burning fuel becomes thinvor holes are formed therethrough, permitting a too great How of air combustion of through, the heating eiiiciency will be reducedand the flow of air through the fire box into the furnace must be reduced until the fuel is restored to normal conditions. On the other hand, if the feed of fuel is such that suilicient air cannot be forced through the bed to permit of a complete the gases generated, the rate of feed of fuel should be reduced and preferably the feed of air increased.

In the practice of the invention, provision is made for regulating the flow of air to the fire box by any suitable means known in the art and gases and products of combustion from the furnace by the employment of any suitable means known in the art, such for example as the damper shown at the top of the stack. Under normal conditions, z'. e., with a fuel bed of proper thickness and without any holes or openings therethrough, the means controlling the flow of air to the fire box and the damper on the stack are adjusted so as to maintain such a pressure within the fire box as has been found to exist with a rate of combustion in the re box necessar to produce the desired heat conditions.

convenient method of also for regulating the How ofl regulating the flow of air through the fire box by and in accordance with the pressure of gases in the latter, consists of a furnace-pressure-actuated de-v vice such as described and shown in Letters Patent N o. 1,150,097, dated August 17th, 1915. A conduit l having one end connected to the fire box 2 of the furnace projects up withinan inverted shell or bell of the device A shown in said patent, andas the lower edge of this bell or shell is immersed in a liquid, any change of pressure in the furnace will cause a corresponding change in the position of the bell, the latter raising when the pressure increases and dropping when the pressure diminishes. This bell is connected by a suitable means to a valve mechanism controlling the flow of fluid under pressure to and from the iuid pressure cylinder 3. The piston of this cylinder is provided with a rod 4 extending through opposite ends thereof and one end connected in an suitable manner to suitable means where flow of air through the conduit to the ashpit of the furnace may be varied. In the construction shown, air is forced by a blower (not shown) through the conduit 6 into the y thel the bed of fuel, or openings fuel, the piston fire box, its rate of flow being controlled byl a damper 5, connected by suitable means to the rod 4 of the cylinder 3. A convenient form of connection consists of a cord or other flexible means 7 extending from the piston rod 4 around suitable guide pulleys 8 and connected to` the drum 9 on the shaft of the damper 5. The damper 10 controlling the flow of gases from the furnace is similarly connected by a cord 1 1 to the piston rod 4.

As the pressure in the fire box 2 changes, e. g., increases by reason of the thinness of therethrough, thereb permitting an increased flow of air into t e firebox, the piston A'rod 4 Will, through the described mechanism, be so shifted as to effect a progressive closing of ythe dampers 5 and 10. At the same time,

provision is made for a corresponding increase of feed of fuel so as to restore the bed of fuel in the fire box to normal thickness and close any holes or openings therethrough. Toefect this increase of feed of rod 4 is connected to one end of a lever 12 having its opposite end connected to the movable element of a valve mechanism 13 which controls the flow of steam or other fluid through pipe 14 to the motor 15 of the stoking mechanism. As fuel is fed to the furnace, the flow of air from the conduit will meet with resistance due to the increased quantity of fuel so that the pressureV in the fire box Will be reduced. This reduction in pressure will effect, through the described mechanism, a gradual opening of the dampers 5 and 10 so as to permit such anincrease in the flow of air as is required for the combustion. of the fuel so fed. As the pressure actuated controlling .mechanism will respond to small changes of pressure in the fire box, the shifting of th means for controlling the flow of air to and the escape of products of combustion from the furnace will be gradual and 'the rate of operation of the fuel feeding mechanism lwill correspond to the incremental changes of pressure.

In some cases it may be desired to so adjust the combustion in the fire box that complete combustion of the gases generated therein will not be effected in the fire box,

provision being made for what is termed a secondary combustion at a point beyond the fire box and in the heating chamber. In such cases, the conduit branch pipe 16 leading to the point at which it is desired to introduce air for the secondary combustion. In order that the air for secondary combu'stion may have. suitable ratio as regards pressure and volume to that supplied for primary combustion,'its flow is controlled by a damper l?. This damper is controlled by the movement of the piston rod 4 of the cylinder 3 so as to be opened fire box were normal. a substantially uniform pressure in all parts movement, operating as 6 is provided with a and closed as the pressure rises and falls in the firebox or heating chamber.

Some furnaces have their stack connection located a considerable distance from the firebox and the charging or discharging doors so located that the opening of either or both of the doors will cause a change of pressure which would affect the controlling mechanism although conditions in the In order to maintain of the furnace, provision is made for controlling the stack damper by and in accordance with pressures in the stack or portions of the furnace at a distance from the fire box.

While in such cases, two independent pressure actuated devices'such as shown in Figs. 1 and-2 and hereinbefore described, may be employed, one .of the mechanisms being connected to the fire box by a conduit is employed for adjusting the feed of air and fuel to the fire box, while the other mechanism is connected to the stack or other part of the furnace and is employed for shifting the stack damper. It is preferred, however, to employ the twin mechanism shown in Figs. 3, 4 and 5. This mechanism consists of a tank or shell 20, which is preferably constructed with enlargements at its ends in which are arranged one member of each pair of inverted cups 21 and 22, the members of each pair being connected to the re-l` spective ends of levers 23AV and 24. These` cups are made of substantially equal dimensions and are so supported by the levers as to be partially submerged in the liquid contained in the tank. Conduits 25 and 26 leading from the different portions of the furnace as hereinafter described, project up 105 into the one cup of 'each pair, so that any change of pressure in the portions of the furnace to which the respective conduits are connected, will cause movement of the cups. rOne of the cups of each pair is ac- 110 tuated in accordance with changes of pressure and the other serves to control such a fluid pressure cushion limiting the extent of movement of the pair and servingto'restore the pair to 115 normal position after being moved by changes in furnace pressure. The Acushioning effect is regulated by'admittin more or less air'into the adjusting cups t rough valvesl 27. The pivotal shafts of theflevers 23 and 24 are provided with arms 28 and 29, having their outer ends connected by bellcranks `to valve mechanisms 30 and 31 adapted to control the ow of fluid under pressure to and from the respective ends of cylinders 32 and 33. The rod 34 connected to the piston of the cylinder 32 is connected by any suitable means such as the cord 35 to the damper 5 in the air conduit. The rod 36 connected to the piston 130 of cylinder 33 is connected by suitable means such as the cord 37 to a damper controlling the flow of products of combustion from the furnace.

The piston rod 34 has its lower end connected by a lever 38 to the stem of a valve mechanism 39 controlling the flow of Huid under pressure through the pipe 14 to the motor 15 of the fuel feeding mechanism, as the Stoker.

It -Will be observed that the feed of fuel and air to the fire box is controlled by the part of the mechanism connected by conduit 25 to the fire box, as changes of pressure of gases in the fire box are lmost generally due to changes in the fuel bed. Changes in the pressure of gases in portions of the furnace will be due in most cases to the opening-of charging and discharging doors, and it is not desirable that changes from such causes should affect the conditions of combustion in the fire box, unless the abnormal conditions in the parts of the furnace remote from the fire box should be continued for a relatively long time. Y

In order to prevent fluctuations of vpressure due to the opening of charging or discharging' doors affecting combustion operations, the conduit 26 connected With the other member of the twin regulating mechanism, is connected either to the stack or by a valved branch 40 leading to any desired point of the heating chamber of the furnace. In case of a drop of pressure in or adjacent to the point or points to Which conduit 26 is connected, the cup 22 will be shifted thereby shifting the valve mechanism 32 to admit fluid under pressure to the lower end of cylinder 33, causing an upward movement of the piston of this cylinder and thereby permitting of a closing movement of the valve controlling the flow of products of combustion from the furnace. As soon as pressure in the furnace has been restored to normal, the damper Will be automatically shifted to maintain the normal ypredetermined pressure in the furnace.

In order to adjust the regulating mechanism to operate at any pressure or pressures,

desired in the furnace, countervveights 41 and 42 are slidably mounted on rods 43 and 44 carried by the respective pairs of cups. By shifting these Weights along the rods, the cups Willfbe held stationary except on a change of pressure in the furnace from a normal or predetermined pressure.

The employment of means for controlling the stack damper by and in accordance with variations of pressure in the portions of the furnace remote from the fire box, as the rear portion of the furnace or in the stack, is useful when providing for secondary combustion of the gases after leaving the fire box. Suchv secondary combustion will result in an increase in the volume of gases and scribed, and other forms of fuel.

consequently an increase in pressure in the urnace, and when the stack damper is controlled by and in accordance With pressure in the fire box, the increase of pressure due to secondary combustion will extend back to the fire box and cause a change in the flow of air and thefeed of fuel to the fire box at times when 'combustion conditions in the fire box are normal. But by controlling the damper regulating the flow of products of combustion from thev furnace by variations of pressure intermediate the point of secondary combustion and such damper, any changes due to secondary combustion or other causes, which will affect combustion in the irebox are compensatedfor. It is also desirable to regulate the supply of air for secondary combustion by and in accordance with changes of conditions in portions of the furnace posterior to the point of secondary combustion, and to this end the is connected by any suitable damper 17 cord 45 to rod 36 of the cylinmeans as a der 33.

While the invention is shown and described in connection with solid fuel, it will be readliy understood by those skilledin the art that the flow of other forms of fuel such as liquid or gaseous fuel, can vbe regulated by and in accordance with the pressure of gases in the furnace., and under the term furnace is included both the fire box and stack, through the mechanism decorresponding changes can be made in the flow of air necessary for the support of combustion by using such This application is filed in place of application Serial Number 206464 filed December 10,n 1917, but `became abandoned February 23, 1919.

We claim herein as our invention:

1. The method herein described of controlling combustion which consists in reguof air for combustion in a furnace by and in accordance with the pressure of gases in the-furnace and-varying the rate of feed of fuel inversely to the rate of supply of air.

The combination lating the supply of a furnace, means for feeding fuel to the furnace, means for.

causing a flow of air to the furnace for combustion, means adapted to be operated by variations in the pressure of gases in the furnace from a predeterminedstandard for varying the rate of flow of air proportionally to changes of pressure in the furnace and means for varying the rate of feed of fuel inversely proportional to the 4flow of air.

3. The method herein described'of controlling combustion in furnaces, which consists in varying the flow of air and the feed of fuel'by and in accordance with variations in the pressure of gases in the furnace, one

inversely and 

